High temperature bis (epoxyalkyl) carborane adhesives

ABSTRACT

The process of providing an adhesive junction between two workpieces having opposing smooth surfaces comprising the steps of mixing material selected from the group consisting of bis(epoxybutyl)carborane, bis(epoxypentyl)carborane, and bis(epoxyhexyl)carborane, with a curing agent selected from the group consisting of boron trifluoride ethylamine and 4,4&#39;&#39;diaminodiphenylsulfone, applying said mixture to the opposing surfaces, joining the surfaces and allowing the workpieces with the mixture therebetween to harden under heat and pressure.

United States Patent 91 Barnes et al.

111 3,725,176 [451 Apr. 3, 1973 [54] HIGH TEMPERATURE BIS (EPOXYALKYL) CARBORANE ADHESIVES [22] Filed: Feb. 4, 1971 [21] Appl. N0.: 112,821

Related U.S. Application Data [62] Division of Ser. No. 762,614, Sept. 25, 1968, Pat. No. 3,669,993.

[52] U.S. Cl ..l56/330, 161/186 [51] Int. Cl. ..B32b 27/38 [58] Field of Search ..l6l/l84, 186; 156/330, 308

[56] References Cited UNITED STATES PATENTS 2,815,309 12/1957 Ganahl et al. ..l56/33O X Nelson et al ..156/330 x 2,951,778 9/1960 Haberlin ..156/33O X 2,970,130 1/1961 Finestone ..156/330 X 3,301,804 1/1967 Zora et a1...

3,480,471 11/1969 Rembold 3,592,711 7/1971 Senarclens et al.

3,678,131 7/1972 Klapprott et all ..156/330 X Primary Examinerl-larold Ansher Attorney-S. A. Giarratana et al.

[57] ABSTRACT The process of providing an adhesive junction between two workpieces having opposing smooth surfaces comprising the steps of mixing material selected from the group consisting of bis(epoxybutyl)carborane, bis(epoxypentyl)carborane, and bis(epoxyhexyl)carborane, with a curing agent selected from the group consisting of boron trifluoride ethylamine and 4,4-diaminodiphenylsulfone, applying said mixture to the opposing surfaces, joining the surfaces and allowing the workpieces with the mixture therebetween to harden under heat and pressure.

8 Claims, No Drawings HIGH TEMPERATURE BIS (EPOXYALKYL) CARBORANE ADHESIVES This is a division of Application Ser. No. 762,614, filed Sept. 25, 1968, now US. Pat. No. 3,669,993.

The invention described herein was made in the performance of work under a NASA contract andis subject to the provisions of Section 305 of the National Aeronautics and Space Act of 1958, Public Law 85-568 (72 Stat. 435; 42 U.S.C. 2457).

The present invention relates to the preparation of bis(epoxyalkyl)carborance monomers, alkenyl intermediates leading to these monomers, and formulations based on these monomers which are useful for room temperature and high-temperature adhesive applications.

Generally speaking, bisalkenylcarborane intermediates which are the subject of the present invention have the following structure a. x l; 1,2-Bis(2-propenyl)carborane b. x 2; l,2-Bis(3-butenyl)carborane c. x 3; 1,2-Bis(4-pentenyl)carborance d. x 4; l,2-Bis(5-hexenyl)carborane e. the isomeric compound l,7-bis(3-butenyl)-neocarborane. These compounds can be converted to the corresponding terminal epoxy derivatives having the following structure i CH2CH(CH2)1C C(CH1)xCH-CHQ \1(3)1{H10 \O/ The following compounds are also characterized herein. 3

a. x l; 1 ,2-Bis(epoxypropyl)carborane b. x 2; 1 ,2-Bis(epoxybutyl)carborane c. x 3; 1,2-Bis(epoxypentyl)carborane d. x 4; 1 ,2-Bis( epoxyhexyl)carborane e. the isomeric compound l ,7-Bis(epoxybutyl)-neocarborane. These epoxies can be cured to hard solids by catalysts and/or reactive hardeners to form a polymer having the following repeating unit in its general structure.

CH2CH0--- 613 loHiu t It is also to be observed that polymers from monoepoxyalkylcarboranes have been investigated and displayed no adhesive properties. These monoepoxyalkylcarboranes have the following repeating structural formula.

mHio The synthesis of carborane C,B,.,H which is the base material for the present invention has been cordance with the following reactions:

HCCH ZRLl -b LiC-CLl 2RH 0 O loHio ioHio O BIOHIO Bisalkenylcarboranes where x=l,2,3, and 4 were prepared in this way. In addition, the bisbutenyl-derivative (Jr-=2) of meta(neo)carborane was also prepared. The following illustrative examples are given with regard to the preparation of these compounds.

Example 1: 1,2-Bis(3-butenyl)lcarborane: x=2

A slight excess of '1 .6M butyllithium solution in hexane (135 ml or 0.216 moles of BuLi) was transferred to a dropping funnel in a nitrogen-filled glove bag. The solution was added over a 15-minute period, with stirring, to 1 1.5g (0.0800 moles) of carborane dissolved in 75 ml of anhydrous ethyl ether contained in a round bottom reaction flask. During addition, a nitrogen flow was maintained over the system, and the flask was cooled with an ice-water bath. After addition was complete, the suspension of heavy white solid was stirred at room temperature for one hour. The suspension was allowed to settle, and the bulk of the supernatant liquid was removed with a syringe. About 75 ml of anhydrous ethyl ether wasadded to the system with stirring to wash the solid. The bulk of the solution was removed, and the procedure was repeated. About 100 ml of anhydrous ethyl ether was added, and the mixture was heated to reflux. A weighed quantity of 4-bromo-1- butene (27.0g 0.200 moles) was added to the system over a 10-minute period. After a two-hour reflux period, the reaction mixture was pouredinto 200 ml of water and thoroughly mixed. The ether layer was separated and dried with magnesium sulphate. The crude product, obtained from the removal of the ether solvent on a rotary evaporator, was fractionally distilled under vacuum (0.1 mm) and the fraction which evolved at a head temperature of l50170C was collected and crystallized. The colorless solid (14.3g representing a 76 percent conversion of carborane to desired product) had a m.p. range of 70-72 C. Gas chromatographic and infrared analyses indicated that the sample was 98 percent pure and an elemental analysis was in excellent agreement with the expected values.

Calcd. for B C l-l 'B,42.8;C,47.7;H,9.5 Found: B,42.4;C,48.2;H,9.5 i

7 Example 2: l,2-Bis(4-pentenyllcarboranezlx=3 The procedure described above for the preparation The crude product was distilled under vacuum (0.1 mm) and the fraction which evolved at a head temperature of 150C was collected as a colorless liquid (18g representing a conversion of 72 percent carborane to desired product). Gas chromatographic and infrared analyses indicated that the product was 93 percent pure.

Example 3: 1,2-Bis(5-hexenyl)carborane: x=4 The procedure described above for the preparation of bis(butenyl)carborane was followed using the following amounts of reagents.

150 ml butyllithium solution (0.240 moles of BuLi) 14.4g carborane (0.100 moles) 32g 6-bromo-1-hexene (0.20 moles) The crude product was distilled under vacuum (0.1 mm) and the fraction which evolved at a head temperature of 180C was collected (26.8g of colorless liquid representing a conversion of 87 percent carborane to desired product). Gas chromatographic and infrared analyses indicated that the product was 96 percent pure. Example 4: l,2-Bis(2-propenyl)carborane: x=1

The procedure described above for the preparation of bis(butenyl)carborane was followed except that a longer reflux time (24 hours) was employed. The following amounts of reagents were used.

150 ml butyllithium solution (0.240 moles BuLi) 14.4 g carborane (0.100 moles) 29g allylbromide (0.24 moles) The crude product was distilled under vacuum (0.1 mm) and the product which evolved at a head temperature of 150C was collected (40 g of a colorless liquid representing a conversion of 18 percent carborane to desired product). Gas chromatographic and infrared analyses indicated that the sample was 93 percent pure. Example 5: 1,7-Bis(3-butenyl)-neo-carborane: x=2 The procedure described above for the preparation of bis(butenyl)carborane was followed except that the intermediate step involving purification of dilithio-neocarborane was omitted. The following amounts of reagents were used.

50 ml butyllithium solution (0.800 moles of BuLi) 5.8g carborane (0.040 moles) 10.8g 4-bromo-l-butene (0.795 moles) The crude product was distilled under vacuum (0.1 mm) and the fraction which evolved at a head temperature of 150C was collected (6.2 g of a colorless liquid representing 60 percent conversion of carborane to desired product). Gas chromatographic and infrared analyses indicated that the product was 93 percent ure. p Bis(alkenyl)carboranes could be converted to the corresponding terminal bis(epoxyalkyl)carborane monomers by treatment with trifluoroperacetic acid under carefully controlled buffer conditions in the following manner Y NmC 03 O B roHro Bis(epoxyalkyl)carboranes where x=1,2,3, and 4 were prepared in this way. In addition, the bix(epoxybutyl) derivative (x=2) of meta (neo) carborane was prepared. This is the first reported preparation of these compounds.

Example 6: l,2-Bis(epoxybutyl)carborance: x=-

Trifluoroperacetic acid was prepared in the following manner. Sixty ml of methylene chloride was added to 4.4 ml (0.16 moles) of percent hydrogen peroxide at 0C. A total of 22.8 ml (0.160 moles) of trifluoroacetic anhydride was added to the above solution with stirring over a 10-minute period. Stirring was continued for another ten minutes. A mixture of 100 ml of methylene chloride, 36g of sodium carbonate and 13.2g (0.0520 moles) of bisbutenylcarborane was placed in a three-necked round bottom flask. The flask was equipped with a mechanical stirrer, reflux condenser and a dropping funnel. The solution of trifluoroperacetic acid was added dropwise over a 90- minute period. During this time, the temperature of the reaction was maintained below reflux by the use of an ice-water bath. After the addition was complete, the mixture was refluxed for 30 minutes. Following the reflux period, reaction of a drop of the supernatant liquid to starch-iodide paper was negative, indicating the absence of peroxides. Gravity filtration of the reaction mixture followed by removal of solvent from the filtrate on a rotary evaporator gave 4.1 g of a white solid. The sample was distilled under vacuum and the fraction which evolved at a head temperature of 200C was collected and crystallized. The colorless solid (10g representing a 67 percent conversion of alkenylcarborane to desired product) had a melting point range of 68-71C. Gas chromatographic and infrared analyses indicated that the sample was better than percent pure and an elemental analysis was in excellent agreement with the calculated values.

Calcd. for B C H O B,38.0:C,42.3;H,8.5 Found: B,38.6:C,42.5;H,8.6

Example 7: 1,2-Bis(epoxypentyl)carborane: x=3

The procedure used for the preparation of bis(epoxybutyl)-carborane was followed using the following amounts of reagents.

2.2 ml 90 percent Hydrogen Peroxide (0.080 moles) 1 1.4 ml Trifluoroacetic Anhydride (0.080 moles) 6.5g 1,2-Bis(4-pentenyl)carborane (0.021 moles) The crude product was distilled under vacuum (0.1 mm) and the fraction which evolved at a head temperature of 200C was collected and crystallized. The colorless solid (5g representing a 68 percent conversion of carborane to desired product) had a melting point range of 6875C. Gas chromatographic and infrared analyses indicated a purity of 95 percent and an elemental analysis was in excellent agreement with the theoretical values.

Calcd. for a c n o B,34.6;C, 46.2;H,9.0 Found: B,33.3;C,45.3;H,9.1

Example 8: l,2-Bis(epoxyhexyl)carborane: x=4

The procedure used for the preparation of bis(epoxybutyl)-carborane was followed using the following amounts of reagents.

4.4 ml of 90 percent Hydrogen Peroxide (0.16

moles) 22.8 ml of Trifluoroacetic Anhydride (0.160 moles) 13.6g of 1,2-Bis(5-hexenyl)carborane (0.043 moles) The crude product was distilled under vacuum (0.1 mm) and the fraction (10.5 g representing a conversion of 73 percent of alkenylcarborane to desired product) which evolved at a head temperature of 225C was collected. Gas chromatographic and infrared analyses of the colorless liquid indicated a purity of 97 percent. An elemental analysis was in excellent agreement with the calculated values.

Calcd. for B C H O B,31 .8;C,49.5;l-1,9.4

Example 9: l,2-Bis(epoxypropyl)carborane: x=l

The procedure used for the preparation of bis(epoxybutyl) carborane was followed except that disodium hydrogen phosphate was used as the buffer in place of sodium carbonate. The following amounts of reagents were used:

2.2 ml of HYdrogen Peroxide (0.080 moles) 1 1.4 ml of Trifluoroacetie Anhydride (0.080 moles) 3.5g of 1,2-Bis(2-propenyl)carborane (0.016 moles) A total of 30g of product (representing an 83 percent conversion of alkenylcarborane to desired product) was isolated. Gas chromatographic and infrared analyses of the solid (melting point 36-48C) indicated a purity of 97 percent.

Example 10: 1,7-Bis(epoxybutyl)-neo-carborane: x=2

The procedure used for the preparation of bis(epoxybutyl)-carborane was followed using the following amounts of reagents.

2.2 ml of 90 percent Hydrogen Peroxide (0.080

moles) 11.4 ml of Trifluoroacetic Anhydride (0.080 moles) 6.6g of 1,7-Bis(butenyl)-neo-carborane (0.026

moles) The crude product was distilled under vacuum (0.1 mm) and the fraction evolved at a head temperature of l50-170C was collected and crystallized. The colorless solid (4.5g representing a conversion of 68 percent of alkenyl-neo-carborane to desired product) had a melting point range of 5 l54C. Gas chromatographic and infrared analyses of the product indicated a purity of 94 percent.

Adhesive Properties Example Lap-Shear Epoxy Number Strength, psi

Bis( epoxybutyl )carborane 12 2320 Bis(epoxypentyl )carborane 13 i 2810 Bis(epoxyhexyl )carborane 14 3600 Representative lap-shear strengths at room temperature are listed below for the epoxies cured with the reactive hardener 4,4-diaminodiphenylsulfone.

Example Lap-Shear Epoxy Number Strength, psi Bis(epoxypropyl)carborane 15 1740 Bis(epoxybutyl)carborane 16 2040 17 2000 Bis(epoxybutyl)-neo-carborane Lap-shear strengths at 400F (:air atmospheres-l0 1 minute hold at temperature) as high as 980 psi have been obtained with the bis(epoxybutyl)carborane- 3phrBF :EtNl-l catalyst system Example 18.

Superior high temperature results are obtained by reacting the bis(epoxyalkyl)carboranes with certain reactive hardeners. Lap-shear strengths as high as 1,730 psi have been obtained at 500F in air when bis(epoxybutyl)carborane was cured with 4,4- diaminodiphenylsulfone (Example Number 19). These values, which represent percent retention of room temperature strength (2,040 psi) were obtained on samples which had been previously soaked at 500F for 2 hours. Lap-shear strengths as high as 1460 psi at 500F in air have been obtained on samples soaked at 500F for 24 hours (Example Number 20). At 440F, percent of room-temperature lap-shear strength is retained (Example Number 21) The following examples relate to preparation of lapshear test specimens, testing procedures, formulations for the various adhesive compositions and test results.

Example 1 1: Preparation of Lap-Shear Specimens and Testing Procedures Nitric Acid (70%) 10% Hydrofluoric Acid (50%) 2% Water On removal from the acid solution, the adherends were thoroughly rinsed with cold water and then immersed in a chromic acid solution for 10 minutes at F. The composition of the acid solution was as follows: I

Sodium Dichromate 28.5g Sulphuric Acid 285g Tap Water To make 1 liter Aluminum Metal 5g After the acid treatment, the adherends were thoroughly rinsed in cold running tap water. Finally, they were rinsed in distilled water, observed to make sure they held a continuous film of water, and dried in an oven for 30 minutes at 160F.'After the degreasing step, all handling was done using cotton gloves.

The adherends were laid up in a special mounting fixture which ensured accurate alignment of the adherends and an exact overlap of 0.50 in. The fixture could take a total of five specimens (10 adherends). The B-staged epoxy was warmed (2l2-300F depending on the test sample) and carefully applied to the adherends. The latter were then warmed with an air gun and the liquid was spread over the overlap surfaces. In some cases, the fixture was placed in a vacuum oven at 212F for 15-20 minutes to outgas dissolved air in the epoxy. A 0.5 inch wide strip of glass cloth (Volan A-l81 or 112) was laid'over the overlap area of the lower adherend, and the upper adherend was then placed over the glass cloth. The lay-up fixture containing the specimens was placed in a Carver Hydraulic Press equipped with heating plates and a modified quick closer attachment to ensure constant pressure. After curing, the specimens were removed from the mounting fixture and filed to remove excess epoxy. The glue line thickness in each specimen was determined by measuring the thickness of each adherend adjacent to the overlap area with a micrometer, followed by measuring the total thickness atthe overlap area. A simple subtraction gave the glue line thickness. All specimens were tested in an lnstron Tensile Tester at a constant strain rate of 0.01 in./in./min. In elevated temperature tests, a specially designed furnace was preheated and placed around the specimen in the lnstron Tensile Machine. A period of to minutes was required to bring the specimens to the test temperature. The specimen was held at that temperature for ten minutes and tested (at temperature).

Example 12 Lap-shear Strength Bis(epoxybutyl)carborane-3phrBF :EtNl-l Test Glue Line Failure Strength Temperature F Thickness in.) psi Composition 1.86 g epoxy 0.06g catalyst B-stage 230-265F for 50 minutes Outgassed No Glass Cloth Style 181 Cure-Assembly 445F, 120 psi, 1 hour Post-Cure None Example 13 Lap-Shear Strength Bistepoxypentyl)carborane-3phrBF zEtNl-l Test Glue Line Failure Strength Temperature F Thickness (in.) psi Composition 1.0g epoxy 0.030g catalyst B-stage 225-260F for 30 minutes Outgassed No Glass Cloth Style 181 Cure-Assembly 445F, 120 psi, 1 hour Post-Cure None Example 14 Lap-Shear Strength Bis(epoxyhexyl)carborane-3phrBF :EtNH,

Test Glue Line Failure Strength Temperature "F Thickness (in.) psi Composition 1.02g epoxy 0.03g catalyst B-stage 230-265F for 30 minutes Outgassed No Glass Cloth Style 181 Cure-Assembly 445F, 120 psi, 1 hour Post-Cure None 5 Example 15 Lap-Shear Strength Bis(epoxypropyl)carborane-48phr 4,4'- I diaminodiphenylsulfone Glue Line Thickness (in.) 0.003

Test Temperature F Failure Strength psi 1 740 Composition 1.52g epoxy 0.73g hardener B-stage 300F for 40 minutes Outgassed Yes Glass Cloth Style 1 12 Cure-Assembly 390F, psi, 2% hours Example 16 Lap-Shear Strength Bis(epoxybutyl )carborane-47phr 4,4 diaminodiphenylsulfone Glue Line Thickness (in.) 0.005

Test Temperature "F 75 Failure Strength psi 2040 Composition 1.51g epoxy 0.71g hardener B-stage 300F for 40 minutes Outgassed Yes Glass Cloth Style 1 l2 Cure-Assembly 390F, 120 psi, 2% hours Post-Cure None Example 17 Lap-Shear Strength Bis(epoxybutyl)-neo-carborane-28 phr 4,4"- diaminodiphenylsulfone Glue Line Thickness (in.) 0.004

Test Temperature "F 75 Failure Strength psi 2000 Example 18 Lap-Shear Strength Bis(epoxybutyl)carborane-3phrBF :EtNI-1 Glue Line Thickness (in.)

Test Temperature F Failure Strength psi 980 Composition 2.01 g epoxy+ 0.06g catalyst B-stage 212F for 1 hour Outgassed Yes Glass Cloth None Cure-assembly 445F, 120 psi, 1 hour Post-Cure None Example 19 Lap-Shear Strength Bis(epoxybutyl)carborane-47phr 4,4- diaminodiphenylsulfone Test Glue Line Failure Strength Temperature F Thickness (int) psi Composition 1.51g epoxy 0.7 lg hardener B-stage 300F for 40 minutes Outgassed Yes Glass Cloth Style 1 12 Cure-Assembly 390F, 120 psi, 2% hours Post-Cure 500F for 2 hours Example 20 Lap-Shear Strength Bis( epoxybutyl)carborane-48phr 4,4- diaminodiphenylsulfone Test Glue Line Failure Strength Temperature F Thickness (in.) psi Example 21 Lap-Shear Strength Bis( epoxybutyl )carborane-30phr 4,4- diaminodiphenylsulfone Test Glue Line Failure Strength Temperature F Thickness (in.) psi Composition 2.02g epoxy 0.160g hardener B-stage 226-302F for 60 minutes followed by 300F for minutes Outgassed Yes Glass Cloth Style 181 Cure Assembly 445F, psi, 2 hours Post-Cure None We claim:

I. The process of providing an adhesive junction between two workpieces having opposing smooth surfaces comprising the steps of mixing material selected from the group consisting of bis'epoxybutyl)carborane, bis(epoxypentyl)carborane, and bis(epoxyhexyl)carborane with a curing agent selected from the group consisting of boron trifluoride ethylamine and 4,4- diaminodiphenylsulfone, applying said mixture to the opposing surfaces, joining the surfaces and allowing the workpieces with the mixture therebetween to harden under heat and pressure.

2. The process of claim 1 where the bis(epoxybutyl)carborane.

3. The process of claim 1 where the his e ox ent l carborane. h proz ss of claim bis(epoxypropyl)carborane.

5. The process of claim 1 where the bis(epoxybutyl)neo-carborane.

6. The process of claim 1 where the bis(epoxyhexyl)carborane.

7. The process of claim 1 where the curing agent is boron trifluoride ethylamine.

8. The process of claim 1 where the curing agent is 4,4'-diaminodiphenylsulfone. i

material is material is l where the material is material is material is UNITED STATES PATENT OFFICE "CERTIFICATE OF CORRECTION Patent No. 3,725,17 Dated p il 3, 1973 Inventor-(s) Robert L. Barnes, I 817. 8.1.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the cover sheet, insert [73] Assighee:

The Singer Company, New York, N.Y.

Signed and sealed this 28th day of August 1973.

(S AL) Attest:

EIMARD MQFLE'I'CHERJR. Attesting Officer RENE D. TEGTMEYER Acting Commissioner of Patents a 

2. The process of claim 1 where the material is bis(epoxybutyl)carborane.
 3. The process of claim 1 where the material is bis(epoxypentyl)carborane.
 4. The process of claim 1 where the material is bis(epoxypropyl)carborane.
 5. The process of claim 1 where the material is bis(epoxybutyl)neo-carborane.
 6. The process of claim 1 where the material is bis(epoxyhexyl)carborane.
 7. The process of claim 1 where the curing agent is boron trifluoride ethylamine.
 8. The process of claim 1 where the curing agent is 4,4''-diaminodiphenylsulfone. 